1. Field of the Invention
The invention relates broadly to fans powered by electric motors and, more particularly, to ceiling fans powered by a.c. induction motors provided with one or more selected speed indicating lamps.
2. The Prior Art
Conventional ceiling fans having a plurality of running speeds, for example, three different speeds are not unusual. The speed changes are often effected by a multiple-position switch actuated by a single pull-chain or the like. The fan blades are relatively large and heavy; consequently, acceleration or deceleration, whenever an operator elects to change speed, is slow because of the inertia not only of the fan blades but the mass of the moving parts of the a.c. induction motor and coupling mechanism which drives the blades. This is a distinct shortcoming because the operator must wait until the selected speed of the fan is, in fact, achieved to make any judgement of which of the available speeds has been selected. This can be aggravating and time consuming. Often over ten seconds or tens of seconds are required to reach the set running speed.
Moreover, even were an operator to wait until the set speed has been achieved, and observe the rotating blades, his conclusion as to the actual speed would be totally subjective and subject to error. The risk of error would be very great, were the operator to have had little or no experience in operating the particular fan involved, and may be impossible in the absence of experience.
Similar disadvantages exist whenever an operator initially turns a ceiling fan on, especially in fan installations wherein the on-off function is effected by one switch and the speed-selecting function is effected by another switch.